tipc: eliminate redundant fields in struct tipc_sock

We eliminate the redundant fields conn_type and conn_instance in
struct tipc_sock. On the connecting side, this information is already
present in the unused (after the connection is established) part of
the pre-allocated header, and on the accepting side, we put it there
when the new socket is created.

Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Hoang Le <hoang.h.le@dektech.com.au>
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>